The "Implementing Recommendations of the 9/11 Commission Act of 2007" (9/11 Act) amended Section 217 of the Immigration and Nationality Act (INA), requiring that the Department of Homeland Security (DHS) implement an electronic travel authorization system and other measures to enhance the security of the Visa Waiver Program. ESTA adds another layer of security that allows DHS to determine, in advance of travel, whether an individual is eligible to travel to the United States under the Visa Waiver Program and whether such travel poses a law enforcement or security risk.